Starter Relay Mounted on the top of the starter

I am trying to find a replacement for the small starter relay mounted to the top of the gear reduction starter used on the 07 Volvo D12. The starter part number is (Volvo)85103338. I know the small relay is a mitsubishi, but I am having no luck finding a replacement part. The dealer only sells the complete starter with the relay bolted to it, but I do not need the entire starter.. Any help would be apreciated.

 

If I could find a high enough rated bosch type relay your suggestion would have worked. But I did not want to modify the existing wiring at all, becuase I am not the only one working on these tractors, we run a fleet of them. I needed a better solution. After searching at length for this part I was finally able to locate one that fit perfect and was a reasonable price. I got it for under $30 shipped. Here is the link to the replacement part I just installed I hope it helps you guys out if you ever run into the same issue.

http://www.texasindustrialelectric.com/relays_10511414.asp